Subject: [Sip] Review of draft-jennings-sip-voicemail-uri-04 by Dean Willis

From: Dean Willis <[email-masked]>
Date: Tue, 1 Nov 2005 17:04:07 -0600

Cullen has (as agreed by the SIP working group) requested publication  
of the individual submission draft-jennings-sip-voicemail-uri-04 as  
an informational-track RFC. I prepared the following brief review to  
assist the RFC editor. If you see problems, please bring them to our  
attention.

----

The format of the document appears to be correct, and the idnits tool  
version 1.82 returned no complaints. The various boilerplate appears  
to be correct. The draft makes no IPR disclosures, and I am unaware  
of any related IPR that should be disclosed. The abstract, though  
brief, seems reasonable.

The examples seem to offer reasonable coverage, and are formatted in  
a manner consistent with "less formal" documents of the SIP working  
group, In particular, the SIP Content-Length header fields are  
elided, with commentary to that effect in-place.

The ABNF grammar reference given in the document is to RFC 2234. This  
reference has expired, and should be replaced with a reference to RFC  
4234. I believe the very simple syntax described in Section 7 of this  
draft is consistent with RFC 4234 to at least the extent that  
existing SIP syntax is so consistent, although I have not applied  
formal verification tools.

The IANA and Security considerations sections of this draft seem  
reasonable, and are consistent with regular usage in standards-track  
documents produced by the SIP working group.

The document, although intended for informative publication,  
normatively references RFC 2119. This requires us to consider  
carefully whether the language of RFC 2119 is being used appropriately.

In the one instance wherein the keyword "MUST" is used (towards the  
end of Section 10.2), the usage is effectively a paraphrase of the  
content of RFC 3323 and 3325, which are referenced in that section.  
As the paraphrase is accurate and consistent with the RFC 2119 usage  
in the referenced documents, I believe this usage of MUST to be  
reasonable.

Section 8 of this draft uses the RFC 2119 keyword "SHOULD" (four  
instances) in relation to a recommended mapping between SIP and PSTN  
cause codes. As this is supported through neither normative  
argumentation nor reference to a normative specification (it is a  
recommendation, not a requirement) I believe this usage would be  
better replaced by a lower-case "should".

Section 8 also uses the RFC 2119 keywords  "SHOULD NOT" and "MAY".  
These terms are also used in a paraphrase of RFC 3325 and are  
consistent with that specification, so I believe this usage to be  
reasonable.

I therefore recommend publication of draft-jennings-sip-voicemail- 
uri-04 as an Informational track document with the following  
"Instructions to the RFC Editor":

Section 8 of the draft uses the RFC 2119 keyword "SHOULD" four times.  
Please replace all four usages with the lower-case string "should".

Please replace the reference to RFC 2234 with a reference to RFC 4234.

--
Dean Willis
SIP co-chair

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip